Method and device for use in DC parametric tests

Abstract

A system and device suitable for use in performing a DC parametric test on an external load is provided. The device may be configured to apply a desired voltage or current to the external load. The circuit device receives a forcing parameter signal at an input and releases at an output a signal approximating the forcing parameter signal to the external load. The circuit device includes a first circuit segment between the input and the output having a search unit, an intermediate voltage point and an internal load between the intermediate voltage point and the output. A second circuit segment connected in a feedback arrangement with the first circuit segment provides the search unit with the voltage at the output. The search unit is adapted for generating a second voltage signal on the basis of the forcing parameter signal and the first voltage signal received and to apply the second voltage signal to the intermediate voltage point. The application of second voltage signal to the intermediate voltage point causes a change in either one of the voltage signal or the current signal at the output such that a signal approximating the forcing parameter signal is caused at the output. A current measuring circuit adapted for providing a measure of the current at the external load suitable for use with a voltage generating circuit device is also provided.

1. A method of performing a DC parametric test on a first load, comprising the steps of:
 a) electrically coupling an output of a second load to the first load;  
 b) applying a first electrical signal to said second load so as to cause a second electrical signal at said output;  
 c) feeding back said second electrical signal to a search entity;  
 d) inputting a forcing parameter signal to said search entity; and  
 e) determining said first electrical signal as a function of said second electrical signal and said forcing parameter signal.  
 
   
   
     2. A method according to  claim 1 , further comprising the step of measuring at least one DC parametric signal corresponding to said first load. 
   
   
     3. A method according to  claim 2 , wherein step a) includes forming an electrically conductive pathway between said second load and said first load and the step of measuring said at least one DC parametric signal includes measuring said at least one DC parametric signal along said electrically conductive pathway. 
   
   
     4. A method according to  claim 1 , wherein said search entity comprises digital search control logic and step e) comprises converting said second electrical signal from an analog signal to a digital signal and converting said first electrical signal from a digital signal to an analog signal, each prior to applying said first electrical signal to said second load. 
   
   
     5. A method according to  claim 4 , wherein step e) further comprises converting said forcing parameter signal from an analog signal to a digital signal. 
   
   
     6. A method according to  claim 1 , wherein step e) comprises generating a digital difference voltage signal dependent on a difference between said forcing parameter signal and a digital approximation of said second electrical signal. 
   
   
     7. A method according to  claim 6 , wherein step e) further comprises converting said forcing parameter signal from an analog signal to a digital signal. 
   
   
     8. A method according to  claim 6 , wherein step e) further comprises processing said digital difference signal to derive a digital voltage signal. 
   
   
     9. A method according to  claim 8 , wherein said first electrical signal is an analog signal and step e) further comprises converting said digital voltage signal to said first electrical signal. 
   
   
     10. A method according to  claim 8 , further comprising the step of allowing said digital voltage signal to settle to a digital target voltage over a period of time. 
   
   
     11. A method according to  claim 10 , further comprising, after the step of allowing said digital voltage signal to settle, the step of measuring at least one DC parametric signal corresponding to said first load. 
   
   
     12. A method according to  claim 1 , wherein step d) comprises inputting a forcing voltage signal. 
   
   
     13. A method according to  claim 1 , wherein step d) comprising inputting a forcing current signal. 
   
   
     14. A method according to  claim 1 , wherein the first load responds to said second electrical signal with an output current flowing between the first load and said second load and the method further comprises the step of measuring said output current. 
   
   
     15. A method according to  claim 14 , wherein the step of measuring said output current includes determining said output current as a function of said forcing parameter signal and said first electrical signal. 
   
   
     16. A method according to  claim 15 , wherein the step of measuring said output current includes the step of determining said output current as a function of a digital approximation of said forcing parameter signal and a digital approximation of said first electrical signal. 
   
   
     17. A method according to  claim 16 , wherein the step of determining said output current comprises performing a look-up using said digital approximation of said forcing parameter signal and said digital approximation of said first electrical signal. 
   
   
     18. A method of performing a DC parametric test on a first load, comprising the steps of:
 a) applying a first electrical signal to the first load;  
 b) generating a second electrical signal as a function of said first electrical signal and a forcing parameter signal; and  
 c) passing said second electrical signal through a second load so that said second load outputs said first electrical signal.  
 
   
   
     19. A method according to  claim 18 , wherein step b) comprises converting said first electrical signal into a digital signal. 
   
   
     20. A method according to  claim 19 , wherein step b) further comprises performing a look-up to determine said second electrical signal. 
   
   
     21. A method according to  claim 18 , wherein said first electrical signal comprises an output current and the method further comprises the step of measuring said output current. 
   
   
     22. A method according to  claim 21 , wherein the step of measuring said output current includes determining said output current as a function of said forcing parameter signal and said second electrical signal. 
   
   
     23. A method according to  claim 22 , wherein the step of measuring said output current includes the step of determining said output current as a function of a digital approximation of said forcing parameter signal and a digital approximation of said second electrical signal. 
   
   
     24. A method according to  claim 23 , wherein the step of determining said output current comprises performing a look-up using said digital approximation of said forcing parameter signal and said digital approximation of said second electrical signal. 
   
   
     25. A method of performing a DC parametric test on a first load, comprising the steps of:
 a) applying a first electrical signal to the first load;  
 b) receiving a forcing parameter signal;  
 c) causing said first electrical signal to approximate said forcing parameter signal as a function of a feedback signal of said first electrical signal and said forcing parameter signal; and  
 d) measuring a DC parametric signal of the first load, said DC parametric signal being a response of the first load to said first electrical signal.  
 
   
   
     26. A method according to  claim 25 , wherein step a) includes applying said first electrical signal to the first load along an electrically conductive path and said DC parametric signal occurs along said electrically conductive path. 
   
   
     27. A method according to  claim 26 , wherein said DC parametric signal is a current signal and step d) comprises determining said current signal as a function of said forcing parameter signal and a second electrical signal applied to a second load that generates said first electrical signal as a function of said second electrical signal. 
   
   
     28. A method according to  claim 27 , wherein step d) includes the step of determining said current signal as a function of a digital approximation of said forcing parameter signal and a digital approximation of said second electrical signal. 
   
   
     29. A method according to  claim 28 , wherein the step of determining said current signal comprises performing a look-up using said digital approximation of said forcing parameter signal and said digital approximation of said second electrical signal. 
   
   
     30. A method according to  claim 25 , wherein step c) comprises generating a second electrical signal and passing said second electrical signal through a second load so as to cause said second load to output said first signal. 
   
   
     31. A method according to  claim 30 , wherein the step of generating said second electrical signal includes generating said second electrical signal as a function of said first electrical signal and said forcing parameter signal. 
   
   
     32. A method according to  claim 31 , wherein the step of generating said second electrical signal includes generating a digital difference voltage signal dependent on a difference between said forcing parameter signal and a digital approximation of said second electrical signal. 
   
   
     33. A method according to  claim 32 , further comprising processing said digital difference signal to derive a digital voltage signal. 
   
   
     34. A method according to  claim 33 , wherein said second electrical signal is an analog signal and step c) further comprises converting said digital voltage signal to said second electrical signal. 
   
   
     35. A method according to  claim 25 , further comprising, prior to step d), the step of allowing said first electrical signal to settle over a period of time.